The Ottoman Empire was an absolute monarchy during much of its existence. The sultan was at the apex of the hierarchical Ottoman system and acted in political, military, judicial, social, and religious capacities under a variety of titles.[a] He was theoretically responsible only to God and God's law (the Islamic شریعتşeriat, known in Arabic as شريعةsharia), of which he was the chief executor. His heavenly mandate was reflected in Islamic titles such as "shadow of God on Earth" (Arabic: ظل الله في العالم‎ zill Allah fi'l-alem) and "caliph on the earth" (Persian: خلیفه روی زمین‎ khalife-i ru-yi zemin).[4] All offices were filled by his authority, and every law was issued by him in the form of a decree called firman (فرمان). He was the supreme military commander and had the official title to all land.[5]Ertoghrul served as the elected leader of the Ottomans from 1230 until his death in 1281. In 1281, Ertoghrul's son, Osman, became elected leader of the Ottomans. From 1299 until his death in 1326, Osman served as Osman I "Sultan of the Ottoman Empire."

After the conquest of Constantinople in 1453 by Mehmed II, Ottoman sultans came to regard themselves as the successors of the Roman Empire, hence their occasional use of the titles Caesar (قیصرQayser) of Rûm, and emperor,[4][6][7] as well as the caliph of Islam. Following the conquest of Egypt in 1517, Selim I furthered strengthened the claim of caliphal authority.[b] Newly enthroned Ottoman rulers were girded with the Sword of Osman, an important ceremony that served as the equivalent of European monarchs' coronation.[8] A non-girded sultan was not eligible to have his children included in the line of succession.[9]

Although theocratic and absolute in theory and in principle, the sultan's powers were limited in practice. Political decisions had to take into account the opinions and attitudes of important members of the dynasty, the bureaucratic and military establishments, as well as religious leaders.[5] From the 17th century onwards, the empire entered into a long-term period of stagnation, during which the sultans were much enfeebled. Many of them ended up being deposed by the powerful Janissary corps. Despite being barred from inheriting the throne,[10] women of the Imperial Harem—especially the reigning sultan's mother, known as the Valide Sultan—also played an important behind-the-scenes political role, effectively ruling the empire during the period known as the Sultanate of Women.[11]

The table below lists Ottoman sultans, as well as the last Ottoman caliph, in chronological order. The tughras were the calligraphic seals or signatures used by Ottoman sultans. They were displayed on all official documents as well as on coins, and were far more important in identifying a sultan than his portrait. The "Notes" column contains information on each sultan's parentage and fate. When a sultan's reign did not end through a natural death, the reason is indicated in bold. For earlier rulers, there is usually a time gap between the moment a sultan's reign ended and the moment his successor was enthroned. This is because the Ottomans in that era practiced what historian Quataert has described as "survival of the fittest, not eldest, son": when a sultan died, his sons had to fight each other for the throne until a victor emerged. Because of the infighting and numerous fratricides that occurred, a sultan's death date therefore did not always coincide with the accession date of his successor.[14] In 1617, the law of succession changed from survival of the fittest to a system based on agnatic seniority (اکبریتekberiyet), whereby the throne went to the oldest male of the family. This in turn explains why from the 17th century onwards a deceased sultan was rarely succeeded by his own son, but usually by an uncle or brother.[15] Agnatic seniority was retained until the abolition of the sultanate, despite unsuccessful attempts in the 19th century to replace it with primogeniture.[16]

a12 : The full style of the Ottoman ruler was complex, as it was composed of several titles and evolved over the centuries. The title of sultan was used continuously by all rulers almost from the beginning. However, because it was widespread in the Muslim world, the Ottomans quickly adopted variations of it to dissociate themselves from other Muslim rulers of lesser status. Murad I, the third Ottoman monarch, styled himself sultan-i azam (سلطان اعظم, the most exalted sultan) and hüdavendigar (خداوندگار, emperor), titles used by the Anatolian Seljuqs and the Mongol Ilkhanids respectively. His son Bayezid I adopted the style Sultan of Rûm, Rûm being an old Islamic name for Anatolia. The combining of the Islamic and Central Asian heritages of the Ottomans led to the adoption of the title that became the standard designation of the Ottoman ruler: Sultan [Name] Khan.[65] Ironically, although the title of sultan is most often associated in the Western world with the Ottomans, people within Turkey generally use the title of padishah far more frequently when referring to rulers of the Ottoman Dynasty.[66] The full style of the Ottoman sultan once the empire's frontiers had stabilized became:[67]

b123 : The Ottoman Caliphate was one of the most important positions held by rulers of the Ottoman Dynasty. The caliphate symbolized their spiritual power, whereas the sultanate represented their temporal power. According to Ottoman historiography, Murad I acquired the title of caliph during his reign (1362 to 1389), and Selim I later strengthened the caliphal authority during his conquest of Egypt in 1516-1517, after the last Abbasid in Cairo, Al-Mutawakkil III, surrendered to him. However, the general consensus among modern scholars is that Ottoman rulers had used the title of caliph before the conquest of Egypt, as early as during the reign of Murad I (1362–1389), who brought most of the Balkans under Ottoman rule and established the title of sultan in 1383. It is currently agreed that the caliphate "disappeared" for two-and-a-half centuries, before being revived with the Treaty of Küçük Kaynarca, signed between the Ottoman Empire and Catherine II of Russia in 1774. The treaty was highly symbolic, since it marked the first international recognition of the Ottomans' claim to the caliphate. Although the treaty officialised the Ottoman Empire's loss of the Crimean Khanate, it acknowledged the Ottoman caliph's continuing religious authority over Muslims in Russia.[68] From the 18th century onwards, Ottoman sultans increasingly emphasized their status as caliphs in order to stir Pan-Islamist sentiments among the empire's Muslims in the face of encroaching European imperialism. When World War I broke out, the sultan/caliph issued a call for jihad in 1914 against the Ottoman Empire's Allied enemies, vainly inciting the subjects of the French, British and Russian empires to revolt. Abdülhamid II was by far the Ottoman sultan who made the most use of his caliphal position, and was recognized as caliph by many Muslim heads of state, even as far away as Sumatra.[69] He had his claim to the title inserted into the 1876 Constitution (Article 4).[70]

c12 : Tughras were used by 35 out of 36 Ottoman sultans, starting with Orhan in the 14th century, whose tughra has been found on two different documents. No tughra bearing the name of Osman I, the founder of the empire, has ever been discovered, although a coin with the inscription "Osman bin Ertuğrul bin Gündüz Alp" has been identified.[71]Abdülmecid II, the last Ottoman caliph, also lacked a tughra of his own, since he did not serve as head of state (that position being held by Mustafa Kemal, President of the newly founded Republic of Turkey) but as a religious and royal figurehead.

d^ : The Ottoman Interregnum, also known as the Ottoman Triumvirate (Turkish: Fetret Devri), was a period of chaos in the Ottoman Empire which lasted from 1402 to 1413. It started following the defeat and capture of Bayezid I by the Turco-Mongol warlord Tamerlane at the Battle of Ankara, which was fought on 20 July 1402. Bayezid's sons fought each other for over a decade, until Mehmed I emerged as the undisputed victor in 1413.[72]

e^ : The dissolution of the Ottoman Empire was a gradual process which started with the abolition of the sultanate and ended with that of the caliphate 16 months later. The sultanate was formally abolished on 1 November 1922. Sultan Mehmed VI fled to Malta on 17 November aboard the British warship Malaya.[56] This event marked the end of the Ottoman Dynasty, not of the Ottoman State nor of the Ottoman Caliphate. On 18 November, the Grand National Assembly (TBMM) elected Mehmed VI's cousin Abdülmecid II, the then crown prince, as caliph.[73] The official end of the Ottoman State was declared through the Treaty of Lausanne (24 July 1923), which recognized the new "Ankara government," and not the old Istanbul-based Ottoman government, as representing the rightful owner and successor state. The Republic of Turkey was proclaimed by the TBMM on 29 October 1923, with Mustafa Kemal as its first President.[74] Although Abdülmecid II was a figurehead lacking any political power, he remained in his position of caliph until the office of the caliphate was abolished by the TBMM on 3 March 1924.[70] Mehmed VI later tried unsuccessfully to reinstall himself as caliph in the Hejaz.[75]